A tape or film cassette for an audio or video tape recorder or a movie projector, particularly for an 8 mm. movie projector, is normally constructed so as to take up and rewind a tape or film reciprocally between a pair of reels. Since the rewinding speed of the tape or film becomes very high, both edges of the tape or film receive a high degree of friction between the upper and lower reel surfaces. Therefore, it is necessary to insert a sheet having a low coefficient of friction between the tape or film and the reels as a sliding member.
Hitherto, paper coated with silicone resin or sheet coated with fluorocarbons has been used as the sliding member.
Recently, in order to enable the tape or film cassette to be played continuously for a long time, a correspondingly longer tape or film has been employed, and since the size of the cassette is restricted by the mechanism and configuration of the audio or video tape recorder or movie projector, this longer tape or film has been provided on the same size of reels by providing a tape or film of reduced thickness. However, when the thickness of the tape or film is reduced, both edges of the tape or film become sharper so that the surface of the sliding member is subjected to increased wear, especially upon high speed rewinding of the film or tape. For example, in many cases there is produced a fine skived powder on the surface of the sliding member engaged by the tape or film, and such fine powders penetrate between convolutions of the tape. As the result of this, in the case of an audio tape cassette, not only does this cause noise, but it also causes the winding speed, which should be constant, to vary irregularly. This reduces the high fidelity of reporduction.
Also, since fine grooves are produced on the member with the edges of the tape or film, the tape or film tends to become inserted into the grooves, so that the area of contact between the tape or film and the sliding member is increased, which subjects the tape or film to increased frictional resistance.
As a result, the winding speed of the tape or film becomes irregular. Further, since the thermal conductivity of the conventional sliding member is small, the frictional heat is not dissipated, but accumulates to the extent that the afore-mentioned phenomenon is further increased. In addition, since the conventional reels and tape or film are made of electrically insulating material, static electrical charge being generated due to the friction is not dissipated, the reels and tape or film and the sliding member attract the afore-mentioned fine skived powders and dust, and this causes noise or a bad visual image. For this reason, the high-fidelity of reporduction of the conventional tape or film cassette is reduced.